Help! Advice on bank charges....?

I have just been to see my bank (RBS) to ask about claiming back on the charges i have incurred for direct debits that made me overdrawn. They said they are perfectly within their rights to charge me and i cannot claim them back as they are allowed to charge me £30 per direct debit - but then if thats the case then how come everyone else is doing it!!!!!! What do i do now? Thanks in advance, appreciate the help!

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RBS PPI Claims